feedback5 WE1: 庇护 is one effect per unit — 宴, 余, 缪尔赛思, 赫拉格, 左乐 and 赫德雷 join the shared key (follow-up 18)

gamedata_const ba.protect / PRTS 术语 庇护 "受到的物理和法术伤害降低相应比例（同名效果取最高）": the strongest source holds; the
自选 kits already used battle.applyStrongest('protect'), these six multiplied private cuts with it.

- kits/shared/tier1.js: PROTECT, protectMods, PROTECT_TICK_HOLD and holdProtect (applyStrongest on the shared key).
- 宴 / 赫拉格 / 左乐 (below their HP threshold): refreshed every tick and at each hit on them; 余 (blocking) and 缪尔赛思's
  melee copies at their old cadence; 赫德雷's 庇护 joins the key, his CRU-X 物理伤害 + becomes its own instance. 左乐 keeps the
  PRTS S2 ordering (his own 庇护 newer than his barrier cuts behind it); 行险 drops his own held 庇护 for its 0.1 s
  re-judgement [ASSUMED: another source's returns with its next refresh]. 遥's bubbles stay separate (the client's
  damage_resistance[bonus] multiplies with the common damage_resistance[inf]).

Golden: no scenario moved — no unit of the corpus holds two 庇护 at once, and one source alone cuts exactly as before.

Tests: test/content/feedback5-protect.test.js (new, 2); kits_t6 (余), kits_alt_t6 (缪尔赛思), op_hodrer updated to the
shared key; kits_t1t2, op_helage, op_zuole pass. Docs: SIM.md §3, kits/README.md checklist 9.

test/content/kits_t6.test.js

@@ -281,8 +281,8 @@ test('余: blocked enemies take 40 % ATK arts + 12 % burn per second, 庇护 whi
   assert.ok(dot.length >= 2);
   const burn = h.dmg.filter((d) => d.src === u.id && d.element === 'burn');
   assert.ok(burn.length >= 2);
-  // 庇护 (ba.protect): physical and arts damage only
-  assert.ok(u.findBuff('yu:shelter') && near(u.s.physTakenMul, 1 - t0.damage_resistance) && near(u.s.artsTakenMul, 1 - t0.damage_resistance));
+  // 庇护 (ba.protect): physical and arts damage only — the shared effect of every source (kits/shared/tier1.js holdProtect)
+  assert.ok(u.findBuff('protect')?.source === u && near(u.s.physTakenMul, 1 - t0.damage_resistance) && near(u.s.artsTakenMul, 1 - t0.damage_resistance));
   assert.equal(u.s.trueTakenMul, 1, '庇护 does not reduce true damage');
   assert.equal(u.s.dmgTakenMul, 1);
   const base = u.base.maxHp;